Circuit controller



March 19, 1929. J, w. McNAlRY. 1,706,124

CIRCUIT CONTROLLER Filed April 20. 1925 Fig.1.

Inventor:

Jacob W Mc Nairq,

His Atto e 40 controlled circuit.

Fatented Mar. 19, 1929.

UNITED STATES 4 1,706,124 PATENT OFFICE.

Q'AGGB W. BICNAIBY, OF SCHENECTADY, NEW YORK, ASSIGNQR '20 GENERAL ELEQEIEZXU GOMPANY, A CORPDRATION OF NEW YORK.

GIRCUIT GONTBOLL'E'R.

Application filed April 20, 1925. Serial 210.2%436.

This invention relates to electro-respon- .sive circuit controlling devices and more particularly to automatic circuit interrupters which are provided with current responsive 5 operating means arranged to operate quickly in response toeither steady or transient predetermined cur'rent conditions. The object ofthe invention is to provide means for changing the calibration of anelectro-re sponsive circuit controlling device of the above character.

Briefly, the change in calibration of the electro-responsive device is accomplished in accordance with my invention by means of an inductive shunt which is permanently connected to the terminals of the currentresponsive means which controls the operation of the circuit controlling device and which is provided with connections intermediate its ends for varying the division of the current between the means and theshunt and thereby varying both the steady and the transient value of currents requiredto efifect operation of the device. i r

Although not necessarily limited thereto, the invention is particularly advantageous when employed to calibrate a high speed automatic circuit interrupter of the "type described and claimed in the Tritle Reissue Pet cut No. 15,441-datedAugust 29, 1 922. The Tritle type of high speed circuit interrupter is strongly biased'to the open position'and is held closed electromagnetically. Current responsive means such as'a winding or bucking bar energized responsively'to the current in the control circuit is arranged to quickly shift the flux of the holding electr'omagnet for cf fecting the opening of the interrupter upon the occurrence of overload conditions inthe Ordinarily or bucking bar of this type of circuit interrupter is connected in parallel circuit with a shunt having relativel large inductance. Due to the inductive c aract-eristics of the shunt the division of current between the operating winding or bucking bar and the shunt variesin accordance with the rate of change of the current in the controlled circuit and hence the interrupter operates at a lower; value of current in the controlled circuit when the winding operate at different values of both steady overload'current as well as diiferent relative values of rapidly increasing overload current depending upon the number of generators supplying power to the controlled circuit. With all of the generators supplying power to the controlled circuit the inherent current limiting characteristics of the line prevents the combined current of the genera tors from exceeding a certain maximum limit even under severe overload conditions, such as a short circuit or the like, while wit a lesserv number oft-he generators supplymg power to the controlled circuit thevalue of short circuit-ed current in the line may greatly exceed the capacity of the generators. Hence, for proper protection of the generators the relative values of rapidly increasing overload currents, as well as the absolute value of steady overload'current required to operate the circuit interrupter vary with the number of generators supplying power to the controlled circuit. i

The desired calibration readily may be attained by means of my present invention and Fig. 1 of the accompanying drawing diagrammatically illustrates the invention embodied in a-protective system for a circuit supplied by a plurality of generators employ.- ing ahigh speed circuit interrupter of .the previously mentioned Tritle type. Fig. 2 of the drawing is an enlarged perspective view of the inductive shunt and bucking bar arrangement of the interrupter shown'in Fig. 1.

In the protective system illustrated, the

'supply line 10 is arranged to receive power from any one or all of the generators 11, 12, 13 and 14, through the respective disconnecting switches 15, 16, 17 and18 and the overload circuit'breakers 19, 20, 21 and 22, which may be of any desired typel The high speed circuit interrupter 23 is arranged to control. a short circuit around the current limiting resister 24 which is inserted in the groundconnection of the generators-11,12, 13 and 14; v

The interrupter 23 as. shownis of the high speed trip freetype described and claimed in the Patent No. 1,560,440, issued Nov. 3, 192.5,

'to John F. Tritle and assigned to theassignee of my present invention and comprises essentially a compound movable circuit controlling member 25 which is strongly biased to the open position in which it is shown by suitable means such as the spring 26. The circuit controlling member 25 is held in the circuit closing position when operating thereto by the closing mechanism 27 under the control of the holding clectromagaet 28. The hold ing electro-magnet 28 is magnetized by a holding winding 29 which is normally energized from the supply line 10 with the voltage reducing resistor 30 in circuit therewith In order to effect the opening of the circuit controlling member 25, a winding or bucking bar 31 is disposed between the poles of the holding electromagnet 23 as described and claimed in the Tritle Reissue Patent No. l5,-l l-l, dated August- 29, 1922, and as more particularly described and claimed in the application, of Leonard Haag, S12, No. 560,216, filed May 10, 1922 and assigned to the assignee of my present invention rsc as to quickly shift the flux of the holding electro magnet upon a predetermined energization of the winding or bucking bar 31.

In accordance with my invention the degree of energization of the windingor bucking bar 31 upon both steady and transient overload current conditions is controlled by means of the inductive shunt 32 which, as more clearly shown in Fig. 2, is permanently connected across terminals of the windor huclring bar and is provided with a plurality of connections 3 L. and intermediate its ends for connecting different portions of the shunt in series circuit relation with the bucking bar and thereby varying the division of current between the remaining portion of the shunt and the bucking bar 31. Preferably these connections correspond in number to the number of generators supplying power to the circuit control interrupter and are under the contrpl of a suitable switch 37 which may be operated to make the proper connection to the shunt 32 depending upon the number of generators supplying power to the control circuit. While my present invention may be carried into effect with any suitable form of inductive shunt, it is illustrated in' the drawing as applied to. a. well known form of inductive shunt comprising a bar 37 of copper or other suitable conducting material which is encircled by a plurality of iron washers '38, preferably located in groups on each side of the connections 35 and 36 as indicated in the drawing. The bar 37 is permanently connected at both of its ends to the terminals ,of the bucking bar 31 and is secured thereto by the bolts 39 and 40. While not shown in the drawing, suitable spacers may be provided for maintaining the groups of washers in proper spaced relation and the washers also may be slotted or otherwilse suitpower circuit through the connection of y the shunt 32. Under these conditions, the circuit interrupter 23 is operated to the closed position upon closure of the normally opened push button 38. This energizes the electromagnet closing mechanism 27 with which the breaker is provided and the resulting operation thereof serves to move the circuit controlling member 25 to the closed position wherein it is electromagnetically held by the holding elcctromagnet 28. the magnetizing winding 29 being normally energized from the supply line 10 or other suitable sources.

The automatic operatin of t interrupter to the open position e occurrence of steady or graduall increasing overload in the controlled circuit depends upon the relative ohmic resistance of the bucking bar 31 and the shunt 32 while the operation of the interrupter 23 responsively to transient or rapidly increasing overload currents in the control circuit also depends upon the relative inductance of the bucking bar 31 and the shunt 32. With the power circuit extending through the connection 33 of the shunt, the arrangement is such-that both the maximum ohmic resistance of the shunt and the maximum inductance of the shunt cause the power current to be divided between the bucking bar 31 and the shunt 32 with the maximum proportion of the current passing through the bucking bar 31 under both steady and transient overload current conditions in the control circuit. Preferably, this arrangement causes the interrupter 23 to open upon the occurrence of a steady current in the supply circuit of a value beyond the safe operating limits of the generator 11 while the operation ppon the occurrence of transient or rapidly increasing overload current occurs at a somewhat lower value such as for example 50% oi the steady overload current. If, now, the disconnecting switch 16 and the circuit breaker 20 are closed to enable the generator 12 to supply current to the supply line 10, the switch 37 is advanced to its second operating position in which the power circuit is established through the connection 34 of the shunt 32 in order to obtain the proper calibration of the interrupter 23. In this case the relative ohmic resistance of the shunt 32 to the bucking bar 31 is decreased although the relative inductance of'the shunt IUD and the bucking bar are substantially the same. Hence the operation of the circuit interrupter to the open position occurs at a higher value of steady or gradually increasing overload current in the control circuit while the relative value of the transient or rapidly increasing overload current required for operation of the breaker remains substantially the same, namely Should the service conditions require a greater current in the supply line 10, the generator 13 may be connected thereto by closure of disconnecting switch 1? and the overload circuit breaker 21. At the same time, in order to afford proper protection for the controlled circuit, the switch 37 is moved into its operative position in which the power circuit is completed through the connection 35 of the shunt 32. Under these conditions the bucking bar 31 and the shunt 32 are connected in the control circuit with one portion of the shunt in series with the bucking bar 31 and another portion of the shunt 32 in parallel circuit with the bucking bar 31 and the first section of the shunt 32. The esulting division of current between the shunt 32 and the bucking bar 31 is such that upon steady or gradually increasing overloads the valueof current required for the operation of the interrupter 23 is further increased while the relative value of the transientor rapidly increasing overload, current is increased. This is due to the fact that the section of the shunt 32 which is connected in parallel circuit withthe bucking bar 31 is of less inductance than when the power cir-. cuit is'conipleted through the connections 33 or 34.

When all of the generators 11, 1,2, 13 and 14 are connected to supply current to the supply line 10-, switch 3'? is operated to complete the power circuit through the connection 36 ofthe shunt 32. In this case the section of the shunt 32 connected in parallel with the circuit including the bucking, bar 31 is of minimum ohmic resistance as well as of minimum inductance. Thus larger values of both steady and transient overload currents in the power circuit are required to elfect operation of the interrupter 23. V

The circuit interrupter 23 may be initiall calibrated by means of the electromagnetic plugs 39 and v40 which control the value of .the flux in the magnetic circuit of the holding electromagnet, 28, or by suitable means for varying the energizing current of the hold-. ing winding 29 to adapt the interrupter for operation at the proper values of both steady and rapidly increasing overload currents corresponding to the operating capacities of the individual generators supplying power to the controlled circuit. Thus, "by varying the value of the flux in the holding electromagnet 28 the value of the current in the bucking bar 31 required to eflect release of the circuit controlling-member 35 under both steady and rapidly increasing overload currents may be either increased or decreased. However, after the flux in the holding electromagnet 28 isinitially adjusted to the proper value the subsequent calibration of the interrupter 23 for operation with different numbers of generators connectedto supply power to the controlled circuit, may be edected entirely by operation of the switch 37 to its operating position corresponding to the number of generators in service. It will be observed that no particular sequential operation of the generators is required since the calibration of the interrupter 23 depends only upon the number of generators connected to the controlled circuit.

While I have described the invention in connection with a high speed circuit interrupter for a plurality of generators, it will he evidentthat the invention also may be employed with equal advantage to adapt a high speed circuit interrupter or other electroresponsive circuit controlling device for operation in circuits of difierent capacity.

What I claim as new and desire to secure by Letters Patent of the United States, is

l. The combination with an electro-responsive circuit controlling device having current conducting means for controlling theoperation of the device, of an inductiveshunt having both its ends connected to the terminals of said current-conducting means, and- 'the division of current between said means and the remaining portion of said shunt. I

2. The combination with an electro-responsive circuit controlling device having current conducting means for controllin the operation of the device, of an inductive s unt for said means, and connections whereby one section of said shunt is connected in series with said means in a circuit andanother section 'of said shunt is connected in parallel circuit with said means and said one section of the shunt. r

3. The combination with an electro-responsive circuit controlling device having current conducting means for controllin the operation of the device, of an inductive shunt connected across the terminals of said means,

spons'ive' circuit interru ter having an inductive conductor for e ecting operation of the interrupter, of an inductive shunt having a plurality of sections of substantially fixed inductance and havin bot-h its'ends connected to the terminals 0 said conductor, and connections whereby said conductor and said shunt are connected in the circuit con trolled by the interrupter with a selected number of sections of the shunt in parallel circuit with the conductor and the remaining sections of the shuntin series circuit relation with the conductor.

5. A high speed circuit interrupter comprising a movable circuit controllingmemer biased to the circuit-opening position, an electromagnet for holding the member in the circuit-closing. position, a conductor associated with said electromagnet for releasing said member, an inductive shunt for said conductor, and connections whereby said conductor and shunt are connected inthe circuit 1' controlled by said interrupter with one section of the shunt in parallel circuit with the conductor and another section of the shunt.

6. The combination with a high speed circuit interrupter" having a holding electromagnet and a loopedconductor extending between the poles of said electromagnet and arranged to be energized responsively to the current of the interru ter for eiiecting operation thereof, of an in uctive shunt Connected across the terminals of said conductor, connections secured to difierent intermediate portions of said shunt, and switch mechanism for connecting the interrupter in a circuit through any selected one of said comes-- tions and thereby include a selected portion of the inductive shunt in series circuit relation with said looped conductor and the remainder of the inductive shunt in parallel circuit relation with saidloo ed conductor.

' 7. The combination with a h speed circuit interrupter having a hol ing electromagnet and current responsive means energized in accordance with the current in the circuit controlled by the interrupter for controlling the holding eflect of the said electromagnet to effect operation of the interrupter, of an inductive shunt havin its ends permanently connected to the terminals of said current responsive means and having electrical. characteristics adapted to vary the division of current between said shunt and said means in accordance with the rate of change of cur rent in the said circuit, means for varying the holding effect of said holding electromagnet to change the value of current in said current responsive means required for operation of the interrupter, and connections in termediate the ends of said shunt for connecting diiierent portions of the inductive shunt in series circuit relation with said current responsive means andthereby varying the relative electrical characteristics ofthe circuit including said electroresponsive means and the circuit including the remaintier of the shunt to chan e the division of current between the remainder of the shunt and said current responsive-means.

In witness whereof, I have hereunto set my hand this 18th day of April, 1925.

JACOB W. MGTBAAIRY, 

